Flexible fluid dispensers which collapse when the fluid is expelled have various uses. Recently, interest in these types of dispensers has increased because they provide a relatively inexpensive alternative to aerosol dispensers which use fluorocarbon or other gas as a propellant, and which have become environmentally undesirable.
In this non-aerosol dispenser, the flexible container is disposed within an expandable container. A rubber sleeve surrounds the casing to apply continuous pressure on the container walls and the fluid therein. A valve on the mouth of the container permits fluid to be dispensed as desired. The expelling force is provided by an elastomeric sleeve which surrounds the flexible fluid container and provides the expelling force when stretched to an open position.
U.S. Pat. No. 4,387,833, issued Jun. 14, 1983, incorporated herein by reference, discloses a dispenser having an extra sleeve to keep the rubber sleeve from slipping in the axial direction. This dispenser comprises an inner container having a ringed, outwardly-extending flange, smaller in diameter than the diameter of the valve assembly, which snapped into an inwardly-extending flange on the inside of the outer container's neck, thereby seating the valve assembly within the outer container's neck. The molding of the inner neck area of the outer container, however, may be very difficult and not economically feasible to manufacture.
U.S. Pat. No. 4,964,540, assigned to the assignee of the present application, also incorporated herein by reference, discloses a dispenser with means for collapsing, in a controlled manner, the flexible container which is enclosed in a rigid enclosure. Specifically, a dispenser is disclosed comprising a tubular, pleated container which has been coated with an elastomeric material such as latex and has a plurality of longitudinal ribs in the valleys of the pleats. These ribs enhance the controlled folding of the pleats in the container, until substantially all the fluid disposed within the bag has been expelled. The container has a mouth at one end, to which is secured to a valve. The mouth also helps seat the container within the enclosure. This seating mechanism tends to be difficult to control dimensionally during manufacture due to variations in container neck and associated structures. If these tolerances are too great or too small, the snap ring will not properly engage the outer container.
Further, the device also seems to require a thicker plastic lip in the mouth area, which can create difficulties in molding. Variations in cooling tend to cause dimensional variations in the molded product. Since the crimped valve is clamped to the mouth of the enclosure, variations in dimension of the mouth compound the problem of unstable sealing of the valve assembly to the mouth of the container which will result in a faulty seal or a leaky dispenser.